This research is directed toward two specific goals: (1) to offer a theoretically and empirically sound explanation of why the Follow Through planned variation social experiment did not succeed in raising the level of intellectual performance of disadvantaged children, and (2) to explain why social class affects intellectual achievement. Theoretical explanations will be derived from computer simulation models of family and school social processes. This model is based on, formalizes, and extends numerous findings from empirical studies of children's intellectual achievement. The proposed theoretical studies are premised on the assumption that the model adequately portrays the aspects of educational processes it simulates. This assumption will be tested by gross and fine structure validity tests and empirical research. In the proposed empirical research, a strong effort will be made to test the external validity of these interpretations by consolidating evidence from past empirical studies, and by performing multivariate statistical analyses of pertinent empirical data-sets to corroborate the axioms of the model and derivations from it. The principal investigator has received assurance of the availability of high quality empirical data for secondary analysis, particularly the Cohort III parent, teacher and child data-sets of the National Follow Through evaluation. The proposed theoretical and empirical studies promise to be very worthwhile because they will consolidate findings from previous empirical studies, point out limitations and clarify ambiguities in existing theories, point out gaps in knowledge, guide new empirical research, provide a method for assessing in advance the possible effects of proposed changes in educational policy, provide insight about actual classroom situations, help formulate recommendations for improving teaching, help train teachers, and support the policy of the U.S. to provide every person equal opportunity to receive high quality education.